Increase in efficiency in certain rotating equipment such as gas turbomachinery is dependent upon increased temperature operational characteristics. Oil lubricated bearings inherently have a limited temperature capability which constrains such rotating machinery design either to limited temperature operation or bearing structure location at a lower temperature environment.
Gas bearings offer the capability of operating in a higher temperature environment inasmuch as an oil lubrication system is not required. A characteristic problem of such non-lubricated bearings is that of dry wear at high pressure-velocity (PV) numbers. This is a serious limit to the load carrying capacity of such bearings, especially for extremely high speed operation.
While the present invention, as described in greater detail below, may present an appearance generally similar to the pivoted pad type of journal bearings, significant structural and operational distinctions therefrom are incorporated in the present invention. More particularly, pivoted pad or tilting pad type bearings are based upon a design concept that presents a very closely defined bearing surface which generates a "wedge" shaped configuration to generate a hydrodynamic film of oil lubrication between the bearing surface and the member being supported. Such prior art arrangements not only require very carefully controlled radii, but also must have a carefully located pivot point for the bearing pads in order to achieve successful operation. Examples of such pivoted pad type prior art bearings may be found in U.S. Pat. Nos. 1,595,744; 2,538,746; 3,205,028; 3,687,506; 3,944,304; 3,985,405; and 3,951,475.